The occurrence and sources of Campylobacter spp., Salmonellaenterica and Escherichia coli O157:H7 in the Salmon River, British Columbia, Canada

Abstract

In this study, we wished to assess the prevalence and determine the sources of three zoonotic bacterial pathogens (Salmonella, Campylobacter, and Escherichia coli O157:H7) in the Salmon River watershed in southwestern British Columbia. Surface water, sewage, and animal faecal samples were collected from the watershed. Selective bacterial culture and PCR techniques were used to isolate these three pathogens and indicator bacteria from these samples and characterize them. Campylobacter was the most prevalent pathogen in all samples, followed by Salmonella, and E. coli O157:H7. E. coli O157:H7 and Salmonella isolation rates from water, as well as faecal coliform densities correlated positively with precipitation, while Campylobacter isolation rates correlated negatively with precipitation. Analysis of DNA extracted from water samples for the presence of Bacteroides host-species markers, and comparisons of C. jejuni flaA-RFLP types and Salmonella serovars from faecal and water samples provided evidence that human sewage and specific domestic and wild animal species were sources of these pathogens; however, in most cases the source could not be determined or more than one source was possible. The frequent isolation of these zoonotic pathogens in the Salmon River highlights the risks to human health associated with intentional and unintentional consumption of untreated surface waters.

Occurrence of Diarrheagenic Virulence Genes and Genetic Diversity in Escherichia coli Isolates from Fecal Material of Various Avian Hosts in British Columbia, Canada

“…To our knowledge, this is the first report on the distribution of STEC and EPEC in a wider range of avian host sources in Canada. In most other studies, information about other pathogens has been provided (28,29). In the present study, E. coli virulence genes, stx 2 and eae, known to be associated with human disease were detected in bird fecal samples.…”

“…In Canada, avian fecal material was found to be a large contributor (30 to 60%) of E. coli in beach sands and surface water (27). Furthermore, information about the prevalence of pathogenic E. coli, especially STEC and EPEC, in a wide range of avian host sources is scarce, even though the distribution of Campylobacter, Salmonella, and STEC (at low levels) has been found in a few birds (28,29). The objectives of the present study were the following: (i) to determine the prevalence of diarrheagenic virulence genes in E. coli isolated from fecal samples of diverse avian host sources and (ii) to determine the genetic diversity of these isolates by repetitive element palindromic PCR (rep-PCR) fingerprinting.…”

Distribution and Characterization of Salmonella enterica Isolates from Irrigation Ponds in the Southeastern United States

“…For example, the Salmonella levels in rivers in the southeastern United States showed much stronger correlations (r ϭ 0.44 to 0.77) with elevated temperatures and rainfall measurements preceding sampling, respectively (8). Conversely, a survey of Canadian rivers reported significantly higher prevalence in spring than in summer, although seasonal precipitation was also correlated with increased Salmonella presence (43). Moreover, results showing small but significant positive correlations with temperatures and rainfall are consistent with prior research for central Florida surface water during an overlapping time period (16).…”

Salmonellae in the Environment

“…Water temperature, Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) had influential roles in the presence of salmonellae in high numbers during warmer months in fresh water lakes (Sharma & Rajput, 1996). Similarly, Statistically significant high densities of salmonellae serovars were detected in Salmon River, British Columbia in Canada during the warm seasons (spring and summer) (Jokinen et al, 2010). Positive correlations were found between high rainfall and temperature with the presence of high densities of various salmonellae serovars in August in River Little, Georgia, USA (Haley et al, 2009).…”